Anthropomorphic medical robot arms, for example, serve to assist in particular actions in a medical setting. They can be used to position or manipulate surgical tools such as, for example, endoscopes, biopsy needles, drills or implants. Existing robot systems are either remote-controlled (for example by a remote control input device) or directly manipulated and work partially or completely autonomously.
The company of Barrett Technology Inc., Cambridge, Mass., USA offers a robot arm for use in image-guided surgery and for many other applications under the name “WAM”. This mobile arm, which includes a kinematic chain consisting of a shoulder joint, an elbow joint and a wrist joint, provides a haptic interaction with the user and, therefore, can be manually guided (see also www.barretttechnology.com).
JP 9-190207 proposes restricting the range of movement of the joint angles of a robot manipulator in order to avoid parts of the arm obstructing each other. The range of movement thus is only restricted enough that the overall functionally possible working range of the robot arm can be used, but movements outside this functionally possible range of movement are avoided.
EP 1 296 609 B1 describes a medical positioning device including at least three limbs, wherein joint axes of sequential joints are aligned perpendicularly and optimized such that an attached surgical tool can reach any target on the patient from almost any direction.
US 2002/0050183 A1 describes an anthropomorphic robot arm which is fastened to a torso and includes a structure that minimizes the occurrence of a state in which a small change at the elbow necessitates a large change at the shoulder position.
US 2001/0013764 A1 discloses a manipulator for aligning a surgical instrument with a treatment point, using a manual input control.
A method is known from WO 2003/077101 A3 in which the user of a surgical robot is provided with a haptic feedback, and the arm is positioned in response to an applied force. Using this method, the movement of the arm is restricted to defined trajectories or safety zones by a user guide.
The publication “Development of a generic, force-reflecting manual controller for different scenarios in medical technology” (U. Hagn, Project reports in the 2003 annual report of the Bavarian network of authorities in mechatronics) describes a surgical robot manipulator which can be guided by the user, wherein manipulation forces are measured and counter forces are applied.
The publication “Design requirements for a new robot for minimally invasive surgery” (T. Ortmaier, H. Weiss and V. Falk in: Industrial Robotics: An International Journal, Special Edition on Medical Robotics, 31(6), pages 493 to 498, November 2004) describes a kinematically redundant, surgical robot arm having kinematics and a connection length that are optimized for required working spaces with different minimally invasive surgical activities and with respect to precision.